rocksdb/table/merging_iterator.h
Siying Dong 6189230202 Change RocksDB License
Summary: Closes https://github.com/facebook/rocksdb/pull/2589

Differential Revision: D5431502

Pulled By: siying

fbshipit-source-id: 8ebf8c87883daa9daa54b2303d11ce01ab1f6f75
2017-07-20 17:20:44 -07:00

63 lines
2.1 KiB
C++

// Copyright (c) 2011-present, Facebook, Inc. All rights reserved.
// This source code is licensed under both the GPLv2 (found in the
// COPYING file in the root directory) and Apache 2.0 License
// (found in the LICENSE.Apache file in the root directory).
//
// Copyright (c) 2011 The LevelDB Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file. See the AUTHORS file for names of contributors.
#pragma once
#include "rocksdb/types.h"
namespace rocksdb {
class Comparator;
class InternalIterator;
class Env;
class Arena;
// Return an iterator that provided the union of the data in
// children[0,n-1]. Takes ownership of the child iterators and
// will delete them when the result iterator is deleted.
//
// The result does no duplicate suppression. I.e., if a particular
// key is present in K child iterators, it will be yielded K times.
//
// REQUIRES: n >= 0
extern InternalIterator* NewMergingIterator(const Comparator* comparator,
InternalIterator** children, int n,
Arena* arena = nullptr,
bool prefix_seek_mode = false);
class MergingIterator;
// A builder class to build a merging iterator by adding iterators one by one.
class MergeIteratorBuilder {
public:
// comparator: the comparator used in merging comparator
// arena: where the merging iterator needs to be allocated from.
explicit MergeIteratorBuilder(const Comparator* comparator, Arena* arena,
bool prefix_seek_mode = false);
~MergeIteratorBuilder() {}
// Add iter to the merging iterator.
void AddIterator(InternalIterator* iter);
// Get arena used to build the merging iterator. It is called one a child
// iterator needs to be allocated.
Arena* GetArena() { return arena; }
// Return the result merging iterator.
InternalIterator* Finish();
private:
MergingIterator* merge_iter;
InternalIterator* first_iter;
bool use_merging_iter;
Arena* arena;
};
} // namespace rocksdb